This disclosure relates generally to maintaining flow of air to an auxiliary power unit and, more particularly, to inhibiting ice buildup within an auxiliary power unit air inlet assembly.
Turbomachines extract energy from a flow of fluid as is known. During operation, air is pulled into the turbomachine. The air is then compressed and combusted. The products of combustion expand to rotatably drive a turbine section of the turbomachine.
One example turbomachine is an auxiliary power unit (APU). The typical APU is located in the tail section of a commercial aircraft. The APU provides electrical power and compressed air to the aircraft. An inlet air assembly delivers air from the environment surrounding the aircraft to the operating APU. The air is typically very cold in flight.
As known, the APU generates significant noise during operation. The noise can propagate through the inlet air assembly and disturb passengers on the aircraft and the surrounding environment on the ground. Accordingly, the inlet air assemblies of many APUs incorporate a noise attenuation device. The cold air delivered to the APU flows past the noise attenuation device. The cold air can result in ice forming on or near the noise attenuation device. Once formed, the ice can undesirably block the flow of air moving to the APU through the inlet air assembly. Ice can also break off and foul the engine.